Photographic prints produced by silver halide chemistry has been a popular means for people to share memories and experiences. These photographic prints are produced by optical exposures on photographic receiver coated with sensitized materials. Photographic prints are of high quality, low cost, and easy to use. These attributes have largely been responsible for the success of photography in the last 100 years. One requirement for a digital printer used in a minilab is that the pictorial images need to be printed at high enough bit-depth to eliminate any perceived contouring (or posterization) image artifacts caused by the quantization in the printed optical densities. Although ink jet printers have been known to produce color images and annotations for homes and offices, no ink jet printing systems are suitable for minilabs.
Another requirement for a digital printer for a minilab is that annotations such as graphics or text can be added to the pictorial image. These may include the date and the location related to the pictorial image, the time of the printing, and copyright symbols. The annotations can be printed within or on the borders of the color image. The color image may also be generated on a computer. As it is well known in the art, annotations such as text and other graphic information are most desirably printed at high resolution so as to have appropriate sharpness.
Yet another requirement for a minilab is that color prints need to be produced at high throughput. Typically, several hundreds of 4" by 6" prints need to be printed within each hour. These color images are normally printed at high ink coverage. Annotations, however, are usually printed at very low ink coverage for most printed color images.